i'm looking for some free music station with no sign-ups to continuously play in a tab in my browser while i do other things... ads are fine but i don't want to have to compile a playlist or anything. just open the page and listen to whatever they choose.

di.fm you can access it either through shoutcast (winamp)/itunes etc under usually the streaming tab. or you can simply download the streaming link files from the website and open them in your media player of choice. I'm partial to the hard dance channel myself. Only has adds once every 15-20 minutes if you're a free user if you sign up for premium $3.99 a month IIRC it eliminates the adds and boosts the audio quality up noticeably. I've been debating signing up for premium as it's nice to just throw on a stream while doing something else and have continous hard dance music pounding through my headphones

Musicovery - Pick a station based on 'mood' with the option to narrow stations by genre.
Grooveshark - Choose a genre or search for an artist for stations.
8Tracks - Listen to user submitted 'mixtapes'.
Bandcamp & Noistrade - Distribution sites for artists, especially up-and-coming ones. Most artists on these sites have music available for streaming.

Also If you are just looking for completely random, try Whys Radio, here is a link to listen on Shoutcast. It is an actual radio station that has no restrictions on genres or content, for example the station will be playing bluegrass, rap, hmong hits, funk, and anything else over the course of a given day.

di.fm you can access it either through shoutcast (winamp)/itunes etc under usually the streaming tab. or you can simply download the streaming link files from the website and open them in your media player of choice. I'm partial to the hard dance channel myself. Only has adds once every 15-20 minutes if you're a free user if you sign up for premium $3.99 a month IIRC it eliminates the adds and boosts the audio quality up noticeably. I've been debating signing up for premium as it's nice to just throw on a stream while doing something else and have continous hard dance music pounding through my headphones

Jelli.com is up there in my favorites along with Pandora and Spotify. You can actually vote and "rocket" songs to be played, chat rooms with every station, small ad breaks on the stations that are fm streamed, cool place.